ORIGINAL PAPER Quaternized poly(1-vinylimidazole) hydrogel for anion adsorption Feyza Genc ¸ 1 • Cengiz Uzun 1 • Olgun Gu ¨ven 1 Received: 22 April 2014 / Revised: 1 April 2015 / Accepted: 25 July 2015 Ó Springer-Verlag Berlin Heidelberg 2015 Abstract Poly(1-vinylimidazole) (PVIm) hydrogels were synthesized through free radical polymerization/crosslinking of 1-vinylimidazole (VIm) in aqueous solutions with azobisisobutyronitrile (AIBN) used as the initiator and N,N 0 -methylenebisacry- lamide (MBAAm) as the crosslinking agent. To quaternize PVIm, dimethylsulfate was used as the methylating agent. Pristine and quaternized PVIm hydrogels were characterized by spectroscopic techniques. Finally, ground hydrogels were used in anion adsorption. The amount of anion adsorbed (in m-eq. anion/g polymer) and adsorption% was determined for fluoride, bromide, nitrite, nitrate, phosphate and sulfate anions using ion chromatography techniques. The amount of phosphate adsorbed on QPVIm hydrogel was the highest and the amount of fluoride adsorbed on QPVIm hydrogel was the lowest. Ion chromatographic study showed that when 1/1 mol ratio of anion to polymer (on a repeating unit basis) was used, 24.7 % of fluoride, 60.6 % of nitrite, 61.6 % of bromide, 63.0 % of nitrate, 99.3 % of phosphate and 98.2 % of sulfate were removed from the medium. Keywords Poly(1-vinylimidazole) Á Anion adsorption Á Hydrogel Á Ion exchange Introduction The presence of some anions in the environment is one of the major concerns due to their toxicity to many life forms. Numerous research efforts are being made to develop methods to remove various types of anions. Most treatment methods to remove anions from waters include chemical precipitation [1], simple and chelating & Olgun Gu ¨ven guven@hacettepe.edu.tr; http://www.polymer.hacettepe.edu.tr 1 Department of Chemistry, Hacettepe University, Beytepe, 06800 Ankara, Turkey 123 Polym. Bull. DOI 10.1007/s00289-015-1479-0